Benzimidazolylstilbene whitening and brightening agents



BENZIMIDAZOLYLSTILBENE WHITENING AND BRIGHTENING AGENTS No Drawing. Application April 21, 1955 Serial No. 503,015

19 Claims. (Cl. 260-240) This invention relates to novel fluorescent compounds of the benzimidazolylstilbene series useful as whitening and brightening agents, to intermediates for the same, and to the preparation thereof.

The present invention provides new fluorescent whitening and brightening agents which are useful in the treatment of threads, sheets, films, filaments, textile fabrics and the like, as well as in the manufacture of paper, varnishes, inks, coatings, and plastics. These new compounds are particularly well adapted to application to white and colored fabrics, especially in the optical bleaching of white fabrics, since they are substantive even in low concentrations to a wide variety of natural and synthetic fibers, they impart a desirable blue-white hue to the white fibers and brighten colored fibers treated therewith, and they have relatively high light stability. Moreover, my invention provides for the first time fluorescent whitening and brightening agents of the stilbene series having the foregoing properties and also having satisfactory stability to chlorine-containing commercial laundry bleaching agents such as sodium hypochlorite and calcium hypochlorite.

The novel compounds of my invention are stilbenes bearing in both the {land 4'-positions benzimidazol-Z-yl radicals which are the same or different and they have the structural Formula I shown below, 1

where R R R and R are radicals of the class consisting of: hydrogen; lower alkyl containing 1-4 carbon atoms, for example methyl, ethyl, isopropyl, and n-butyl; lower alkoxy containing 1-4 carbon atoms, for example methoxy, ethoxy, and n-butoxy; and halo, for example fluoro, chloro, and bromo; and Y and Y are radicals of the class consisting of: hydrogen; lower alkyl containing 1-6 carbon atoms, for example methyl, ethyl, n-propyl, isobutyl, and n-hexyl; hydroxy-lower alkyl containing 2-6 carbon atoms, for example 2-hydroxyethyl and 2,3-dihydroxypropyl; 2-hydroxy-3-sulfopropyl; hydroxy-oxaalkyl containing 3-15 carbon atoms, for example 2-hydroxy-3- (2,3-dihydroxypropoxy)propyl, 2-hydroxy-3-(2-hydroxyethoxy)propyl, and 2-hydroxy-3-[2-(2-hydroxyethoxy)- ethoxylpropyl; carboxy-lower alkyl containing 2-6 carbon atoms, for example carboxymethyl and 2-carboxy- States Patent r 2,838,504 Patented June 10, 1958 2 ethyl; cyano-lower alkyl containing 3-6 carbon atoms, for example 2-cyanoethyl and 3-cyanopropyl; monocyclic aralkyl containing 7-11 carbon atoms, for example benzyl and benzyl containing 1-3 substituents, which can be the same or different, in the benzene ring, as halobenzyl, such ice as ortho-chlorobenzyl, para-fluorobenzyl, 2,4-dichlorobenzyl, and meta-bromobenzyl, lower alkylbenzyl such as orthomiethylbenzyl and para-isopropylbenzyl, and lower alkoxy-benzyl such as p-methoxybenzyl and 3,4-diethoxybenzyl, as well as 2- chloro-4-methoxybenzyl, 3-methoxy- 4-methylbenzyl, 2-methoxy-4-chlorobenzyl, and the like; and allyl and methallyl. i

In general, the compounds of the above structure are high-melting yellow or green-yellow solids which have the following solubility characteristics. They are insoluble in water, hydrocarbons, halogenated hydrocarbons, ketones, ethers and mineral acids. They are moderately soluble in N,N-dimethyl-formamide and dimethyl sulfox-' ide; some of them are soluble in acetic acid; and the compounds wherein at least one of Y and Y is hydrogen are weaklyacidic and soluble in alcoholic alkali to yield contain two or more hydroxyl groups in each radical. The N,N-di alkylated compounds are slightly soluble in lower alkanols, such as ethanol, but this solubility is not increased by addition of alkali.

When the compounds of the present'invention are dispersed in aqueous media, they fluoresce blue-white under ultraviolet light and show a Wide range of absorption in the ultraviolet region. These compounds are substantive to a Wide variety of natural and synthetic fibers, for example, cotton, cellulose acetate, viscose rayon, nylon, silk, and Orlon, and are absorbed by such fibers even from very low concentrations in aqueous dispersions. The compounds have relatively high stability to sunlight, soap, synthetic detergents and chlorine-containing bleaching agents.

The above-described properties of my new compounds make them especially valuable as whitening and brightening agents in treating white and colored fabrics to neutralize the yellowness in white textiles or to enhance the brilliance of colored textiles. In such utilization, the relatively high resistance of my compounds to chlorine bleaching and to light are distinct and surprising advantages, since the previously known whitening and brightening agents of the stilbene series have had as their chief drawbacks a lack of resistance of chlorine-containing bleaching agents and ease of decomposition under influence of light.

A further important advantage of the preferred species of this invention lies in the fact that on repeated applications to white fabrics, thereby building up the amount of the whitening agent on the fibers, the fabrics remain bluish-white and do not develop an undesirable discoloration, for example a red or gray color, such as is produced by many of the known optical bleaching agents when they are applied repeatedly, as for instance in successive launderings.

Although the compounds of my invention are substantially insoluble in water, they are readily utilizable as dispersions in aqueous media. Thus, the treatment of textile fabrics with these compounds is readily carried out by conventional procedures. For example, an aqueous dispersion containing about 0.0001 to 0.5% by weight of the compound and one or more suitable dispersing agents, for instance soap or an organic sulfonate or sulfate, is

This application of the compound can be conveniently carried out in conjunction with a rinsing or washing operation.

The dispersions are readily formed, for example, by dissolving the compoundin a suitable solvent such as N,N- dimethylformamide, alkaline aqueous alcohol, or glacial acetic acid and mixing the solution thus obtained in desired quantity with an aqueous soap or detergent solution. The compounds of Formula I which bear no substituents in the benzene rings of the benzimidazol-Z-yl radicals are much more readily dispersed inthis manner than are the corresponding highly substituted compounds, and it is for this reason that the sum of the carbon atoms in R R R and R in each ring, should be limited to about 16 carbon atoms. When a high degree of dispersibility is a desired feature in the utilization of my compounds, I generally prefer to employ those in which at least two of the radicals R R R and R are hydrogen and the sum of the carbon atoms in all four substituents, in each ring, is no more than two.

A preferred mode of using and marketing the compounds is by incorporating them into solid or liquid soaps and detergents in an appropriate concentration, for example 0.02 to 0.5% of the whitening and brightening agent by Weight.

For incorporation into white detergents, I particularly prefer the symmetrical and unsymmetrical N,N'-bis(oxyalkylated) compounds of my invention having the structural formula N\ -CW Formula IV V wherein Y and Y are the same or different and are members of the group consisting of hydrogen, hydroxylower alkyl radicals containing 26 carbon atoms, and hydroxy-oxaalkyl radicals containing 33-15 carbon atoms, at least one of Y and Y being other than hydrogen. These preferred species of my invention have been found both as individual species and in admixture with each other to have especially high stability in the presence of detergents and to have exceptionally good dispersibility in commercial detergents comprising organic sulfates or sulfonates, for example sodium lorol sulfate and sodium (higher alkyl) benzenesulfonates, and various builders such as sodium triphosphate (also known as sodium tripolyphosphate) and sodium sulfate, in addition to possessing the other advantageous properties common to all of my new compounds as set forth hereinabove. Moreover, repeated application of these compounds (Formula IV) to white fabrics of natural and synthetic fiblers does not cause development of an undesirable co or.

The compounds of my invention can be prepared by employing as starting materials appropriately ortho-substituted bisanilides of 4,4-stilbenedicarboxylic acid. In general, I have found that it is most convenient to prepare the compounds wherein Y and Y in the general Formula I are both hydrogen (Formula III below) by cyclization of a bis-(ortho-aminoanilide) of -a 4,4'-stilbenedicarboxylic acid by heating it under acidic condi- 4 tions; the reaction proceeds in accordance with the following equation.

O H N- R3 C r R3 0 HzN- n -OM- m Rt Formula H Heat iI H RI N as R! M I R3 FormulaIII Usually, I prefer to prepare the bis-(ortho-aminoanilide) starting materials (Formula II) for the above process by reduction of thecorresponding bis-(ortho-nitroanilides). When this is done, it is frequently advantageous to reduce the bis-(ortho-nitroanilide) and then cyclize the resulting bis-(ortho-aminoanilide) directly without isolating it. Thus, the reduction and cyclization reactions are conveniently effected in a single operation by reducing the 4,4'-stilbenedi[carbox(ortho-nitroanilide)] with a mixture of an acid, for example hydrochloric acid or acetic acid, and a metal such as aluminum, iron or zinc and then, if necessary, heating the reaction mixture to etfect cyclization to form the desired 4,4'-bis(benzimidazol-Z-yl)stilbene (Formula III). A mixture of stannous chloride and hydrochloric acid can also be employed as the reducing medium in this method. When an organic acid is employed in the reducing medium, it is frequently advantageous and sometimes necessary to add hydrochloric acid or similar strong inorganic acid to complete the cyclization step. Sodium hydrosulfite can be used as the reducing agent, but when this is done, for best yields the bis(ortho-aminoanilide) should be isolated prior to the cyclization step.

The bis(ortho-nitroanilides) which have the structural formula O2N R2 H G w w OzN R7 i 3 R4 fiuoro-Zmitroanilide) preferred. For best results, a solvent should be employed in carrying out the reaction and for this purpose 2-methoxyethanol, 2-ethoxyethanol, and 75-90% acetic acid have been found to be especially useful.

Using the above process, for example the following compounds of Formula 111 are obtained by reducing the indicated bis-(ortho-nitroanilides) of- 4,4-stilbenecarboxylic acid and cyclizing the corresponding intermediate bis-(ortho-arninoanilide) thereby produced in each in-- stance (as'will be appreciated, the t'automeri'sm of these products affords in many cases alternative choices of designation for a single substance; these choices are indicated hereinbelow, where appropriate, in accordance with conventional nomenclature requirements):

4,4-bis (benzimidazol-Z-yl stilbene, from the his (orthonitroanilide);

4,4-bis[4(or 7) methoxybenzimidaz-ol-Z-yl)]stilbene, from the bis(3-methoxy-2-nitroanilide); v

4,4-bis[4(or 7)-ethoxybenzimidazol-'2-yl]stilbene, from the bis(3-ethoxy-2-nitroanilide); I

4,4-bis[ or 6 -isopropoXybenzimidazol-Z-yl]stilbene; from the bis(5-isopropoxy-2-nitroanilide);

4,4-bis 5,6-dimethoxybenzimidazol-2-yl stilbene, from the bis(4,S-dimethoxy-Z-nitroanilide) 4,4" bis(5,6-dibutoxybenZirnidazol-2-yl)stilbene,. from the his (4,5-dibutoxy-Z-nittoanilide) 4,4 bis[4,5,7( or 4,6,7')'-trimethoxybenZimi'daZol-Z-yl]- stilbene, from the bis(3,5,6-trimethoxy-2-nitroanilide);.

4,4 '-bis[4(or 7) -methylbenzimidazol 2 yl]stilb'ene, from the bis(S-methyl-Z-nitroanilide);

4,4 bis[5 (or 6)-tert-butylbenzimidazol 2-yl]stilbene, from the bis(S-tert-butyl-2-nitroanilide');

4,4-bis(5,6-dimethylbenzimidazol-Z-yl)stilbene, the bis(4,5dimethyl-2-nitroanilide) 4,4 bis(4,5,6,7-tetramethylbenZimidazol-Z-yl') stilbene, from the bis(3,4,5,6-tetramethyl-3-nitroanilide')';

4,4-bis[5(or 6)-ethylbenzimidazol-2-yl]stilbene, from the his (4-ethyl-2-nitroanilide);

4,4-bis[5(or 6)-chlorobenzimidazol-2-yl]stilbene, from the bis(4-chloro-2-nitroanilide) 4,4-bis[5 (or 6) -fluoro-benZirnidazol-2-yl]stilbene, from the bis (S-fiuoro-Z-nitroanilide) 4,4'-bis[4,6 (or 5,7) -dibromo-benzimidazol 2-yl]stilbene,

from

p from the his 3,5 dibromo-2-nitroanilide);

4,4-bis[4-bromo-6,7-methylenedioxy(or 7-b'romo 4,5- methylenedioxy)benzimidazol-2 yl]stilbene, from the bis- (3broom-5,6-methylenedioxy-Z-nitroanilide) and 4,4" bis[5 methoxy-6-methyl(S-methyl-G-niethdxy)- benzimidazol-iZ-yl]stilbene, from the bis'(4-me'thoxy-5- methyl-Z-nitroanilide) The N,N-unsubstituted compounds (Formula III) obtained in the manner described above are useful per se as whitening and brightening agents. They react readily with alkylating agents to yield N-monoand symmetrical or unsymmetrical N,N-di-(alkyl or substituted alkyl) derivatives, so that they are also useful as starting materials for the convenient preparation of the whitening and brightening agents of my inventionof Formula I whereinone or both of Y and Y are alkyl orsubstituted alky-l radicals of the type hereinbeforedefined. The alkylation reaction is readily carried out by heating a 4,4 '-bis( benzimidazol-2-yl) stilbene (Formula III) with the appropriate alkylating agent. Usually a heating period of about one to four hours at 50-125 C. is sufficient to'produce a satisfactory yield of the desired product. The alkylating agents useful in this conversion include for example esters of strong organic and inorganic acids having the formula Z An, where Z is a member of the class consisting of lower alkyl containing 1-6 carbon atoms, hydroxy-lower alkyl containing 2-6 carbon atoms, droxy-3-sulfopropyl, hydroxy-oxaalkyl containing 3-15 carbon atoms, carbo'xy-lower alkyl containing 2-6 carbon atoms, c'yano-lower alkyl containing 3-6 carbon atoms, and monocyclic aralkyl containing 7-1 1 carbon atoms and An is the anion of a strong acid. Illustrative of these esters are: methyl sulfate, ethyl sulfate; methyl p-t'oluenesulfonate; lower alkyl halides, such as methyl chloride, ethyl bromide, butyl chloride, and hexyl chloride; monocyclic aralkyl halides, such as benzyl chloride, p-methoxybenzyl chloride, o-chlorobenzyl chloride, 2-chloro-4-rnethoxybenzyl bromide, and benzyl bromide; allyl and methallyl halides, such as allyl chloride and methallyl bromide; carboxy-lower alkyl halides, such as 2-carbox'ye'thyl chloride and carboxymethyl bromide; cyano-lower alkyl halides, such as 2-cyanoethyl chloride; hydroxy-l'o'wer" alkyl halides, such as 2,3-dihydroxypr'opyl chloride (of glycerol alpha-chlorohydrin), ethylene chlo'rohydrin, ethylene brornohydr'in, isobutylerie chlorohydrin; 2-hy droxy-3-sulfopropyl chloride or bromide; hydfoxy oxaalkyl halides, such as 2-hyd roxy-3-(2-hydroxyethox'y')- propyl chloride, 2-hydroxy-3-(2,3 -dihydroxypropoxy)- propyl chloride and 2-hydroxy-3-[2-(2-hydroxyethoxy')'- ethoxyJ-propyl chloride. Also useful as alkylating agents are 1,2-lower alkylene oxides containing 2-6 carbon atoms, for example, ethylene oxide, propylene oxidefglycidol, and epichlorohydrin; and acrylonitrile and methacrylonitrile.

The N-monoalkylated compounds (Formula I, where only one of Y and Y is hydrogen) are obtained by heating preferably one or advantageously slightly more than one molecular equivalent of the appropriate alkylating agent with one molecular equivalent of the 4,4-bis(benzimidazol-2-yl-stilbene (Formula III). Minor proportions of the corresponding N,N'-dialkylat ed compound (Formula I, where neither of Y and Y is hydrogen) and of unreacted N,N-'-unsubstituted starting material (Formula III), varying in amounts depending in part on the relative proportions of the reactants and in part on the reaction conditions, will be found associated with the N-monoalkylated compound obtained as the chief product of the alkylation reaction. If desired, the N-rnono-alkylated product can be purified, for example by use of suitable solvents, but ordinarily it is unnecessary and uneconomical for practical purposes to effect purification since the mixture is directly useful as a whitening' and'brighteniing agent.

As will be understood, the use of larger proportions of the alkylating agent favors higher yields of the N,N- dialkylated compound. When this is the desired product, there are of course required by theory at least two molecular equivalents of the alkylating agent per equivalent of the 4,4-bis(benzimidazolQ-yl)-stilbene (Formula III); as

a matter of fact, for best conversion to the dialkylated dncing a compound of Formula I wherein Y arid' Y are dilfe'rent alkylor substituted alkyl radiea'ls.

. When'the alkylating agent has a hydroxyl group in its structure, for example a hydroxy-lower alkyl orhydroxyoxaalkyl compound, the hydroxyl function in the result ing N-monoalkylated product (e. g., Formula I, Y =H, Y=hydroxy-lower alkyl or hydroxy-oxaalkyl) interacts with a second equivalent of the same or a diiferent alkylating agent to yield preferentially O-alkylated products rather than the expected N,N-dialkylated derivative, the

latterbeing produced only in relatively small amount."

The use of a large excess of the alkylating agent leads to substantially complete production of N,N'-disubstituted products.

7 Instead of using the alkylation process described above,

analternative method for obtaining N-(Z-cyano-lower alkyl)-. and N,N'-di(2-cyano-lower alkyl)-compounds of Formula I is by interacting an acrylonitrile with the N,N-.unsubstituted starting material (Formula III). The hydrolysis of these monoand di-2-cyano-lower alkyl compounds to the corresponding 2-carboxy-lower alkyl compounds affords an alternative route to the latter substances.

For the preparation of the N,N'-dialkyland N,N'- di(monocyclic aralkyl) compounds of Formula I, there can be employed instead of the alkylation process an alternative method which comprises cyclizing a 4,4-stilbenedi{carbox[ortho-(mono-lower alkylamino or mono monocyclic aralkylamino)]-anilide} by heating it in the presence of an inorganic acid, for example hydrochloric acid, and preferably in a solvent such as 2-methoxy-etha- 1101 or 2-ethoxyethanol. The reaction conditions for this cyclization are substantially the same as for the cyclization of the corresponding ortho-primary amino compounds described hereinabove.

My invention is illustrated by the following examples without, however, being limited thereto.

EXAMPLE 1 4,4'-bis(benzimidazol-2-yl) stilbene A. A solution of 290 g. (2.1 mole) of ortho-nitroaniline in 2860 g. of N,N-dimethylaniline was placed in a tenliter, three-neck flask fitte'd with a high-speed agitator and thermometer and was heated to 50-55 C. To this solution there was then added during a period of three to four minutes a heated (129-132 C.) solution of 305 g. (1 mole) of 4-4-stilbenedicarbonyl chloride in 3580 g. of chlorobenzene. The last remnants of the acid chloride were rinsed from its container into the reaction flask with about 100 g. of boiling chlorobenzene. The temperature of the resulting reaction mixture rose to about 8090 C. and after a few minutes yellow crystals began to separate from solution and the reaction mixture thickened. The reaction mixture was held at 85-90 C. for one hour and was. then stirred at 95-105" C. for eight hours. The reaction mixture was cooled to 25 C. and filtered. The solid cake thus collected was washed successively with 255 g. of chlorobenzene, 475 g. of methanol, and finally with water until a sample of wash liquor was colorless. The yellow product was oven-dried at 80 100 C. There was thus obtained-430 g. of 4,4-sti lbenedi-[carbox(orthonitroanilidefl having the structural formula which melted at 305307 C.

Analysis.-Calculated for C H O N C, 66.00%; H, 3.94%; N, 11.01%; O, 18.85%. Found: C, 65.85%; H, 4.19%; N, 10.61%; 0, 19.30% (direct analysis).

In the preparation of the above dianilide, it was found that the chlorobenzene could be' replaced with orthodichl orobenzene and the N,N-dimethylaniline could be replaced with N,N-diethylaniline to afford the same product in satisfactory yield. The product was also obtained, but in poorer yield and quantity by condensing the reactants ina solventmedium of refluxing chlorobenzene while permitting the hydrogen chloride formed in the reaction to distill off.

B. To a two-liter, three-neck flask fitted with a highspeedstirrer, reflux condenser, dropping funnel, and thermometer there were added 45 g. (0.0885 mole) of 4,4'-stilbenedi-[carbox(ortho-nitroanilide)] and 1125 ml. of Z-methoxyethanol. The mixture was heated to reflux temperature (about 125 C.) and then the outside source of heat was removed. Through the dropping funnel there was added to the mixture a solution of 129 g. (0.575 mole) of stannous chloride dihydrate in 255 ml. of concentrated hydrochloric acid (about 38% by weight) at such a rate that refluxing was quite rapid but well within the capacity of the condenser to prevent loss of solvent; the time required for the addition was about seven minutes. During the addition the temperature of the mixture dropped to about 107 C. After the addition of the reducing agent was completed, the reaction mixture was refluxed for four hours and then was cooled overnight in a refrigerator. The solid which had separated from solution was collected "on a filter and the filter cake was washed free of acid with water as determined by testing with Congo red. The bright yellow powder thus obtained, which was 4,4-bis(benzimidazol- 2-yl)stilbene dihydrochloride, weighed 41 g. This product was suspended in 410 m1. of ethanol and 57 g. of 50% aqueous sodium hydroxide solution was added. The mixture was refluxed until substantially all of the solid had dissolved and was then filtered to remove a small amount of insoluble material. The filtrate was diluted with about four liters of water and filtered to collect the solid which separated from solution. The collected solid was washed free of alkali with water and dried at C. under reduced pressure. There was thus obtained 33 g. of 4,4'-bis(benzimidazol-2yl)stilbene as a pale yellow solid which did not melt when heated to 400 C.

Analysis-Calculated for C, H, N: C, 81.54%; H, 4.88%; N, 13.58%. Found: C, 81.03%; H, 5.10%; N, 13.36%.

The free base was also obtained by dissolving the dihydrochloride in alkaline Z-methoxyethanol, diluting the solution with water, filtering to collect the solid which separated from solution, and washing the product with water until a sample of the wash liquor was free of alkali. This product was identical with the 4,4-bis- (benzimidazol-Z-yl stilbene described above.

The dihydrochloride was not soluble as such in any of the common solvents. The free base was slightly soluble in lower alkanols and in the 2-(lower alkoxy)- ethanols; it was more soluble in N,N'-dimethylformamide; and it was appreciably soluble (up to about 20% by weight) in alkaline 2-n1ethoxyethanol. The free base 9 reacts, with organic and inorganic acids to form the corresponding salts which are all water-insoluble.

EXAMPLE 2 4,4-bis(benzimidazol-Z-yl)stilbene In a 250 ml. flask fitted with an agitator and reflux condenser there were placed 131 g. of glacial acetic acid, 13 g. of water, 2.56 g. (0.059 mole) of aluminum chips, and 1.18 gl of hydrochloric acid (20 Baum). The mixture was agitated vigorously and heated rapidly. Bubbling of hydrogen from the mixture was vigorous when the temperature had reached 70 C., and to the mixture there was then added 10.16 g. (0.02 mole) of 4,4'-stilbenedi[carb0x(ortho-nitroanilide) The reaction mixture was refluxed for four hours, after which there was added 1.76 g. (0.065 mole) of aluminum chips. The reaction mixture was refluxed for a further period of sixteen hours. The product, 4,4-stilbenedi[carbox- (ortho-aminoanilide)], thus formed was not isolated in this instance. Instead, after removal of .the outside source of heat, there was added. to the reaction mixture 69.4 g. of hydrochloric acid (20 Baum) and refluxing was continued for a final period of four hours to effect the desired ring closure. The mixture was then cooled to 25-30" C. and filtered. The solid thus collected was washed with water until a sample of the wash liquor was free of acid as determined by test with Congo red paper. The product obtained, in this manner, which was 4,4-bis(benzimidazol-Z-yl)stilbene dihydrochloride, weighed 9.7 g. It was identical with the dihydrochloride described above in Example 1.

The 4,4-bis(benzimidaZol-2-yl')stilbene dihydrochloride was also obtained insatisfactory yield when iron and 75';9 acetic-acid was substituted for the aluminum and glacial acetic acid in the above procedure.

Treatment of samples of the dihydrochloride obtained above with ethanolic sodium hydroxide yielded in each instance 4,4-bis(benzimidazol-Z-yl)stilbene, identical with the 'base described in Example 1'.

EXAMPLE 3 4,4-bis(benzimizflaaol-Z-yl)stilbene To 271.8 g. of finely ground (20 mesh) crude 4,4-bis- (benzimidazol-Z-yl)stilbene dihydrochl-oride (obtained by the method described above in Example 1) in 3050 g. of 95 ethanol there was added 216 g. of 50% aqueous sodium hydroxide solution. This mixture was heated to reflux to dissolve the solid, and the solution was then filtered to remove about 40 g. of creamy solid consisting chiefly of inorganic salts which failed to dissolve. The filtrate was heated until about 2200 g. of alcohol had been distilled off and to the residue there was added 3.5 liters of cold? water in a thin stream. The mixture was cooled and filtered andthe product thus collected was washed with water until a sample of the filtrate was free of alcohol. There was thus obtained 21t7 g. of 4,4- bis(benzimidazol-2-yl)stilbene.

EXAMPLEA 4 ,4 '-bis( benzimiaflzol Z-yl stilbente In a 100 ml. flask there were placed 25 g. of Z-methoxyethanol, 6.96 g. of sodium hydrosulfite, 2.54 g. of 4,4-stilbenedi[carbox(ortho-nitroanilide)], 1.0 g. of 50% aqueousv sodium hydroxide solution, and: g. of water; This mixture, which was. alkalinev to phenolphthalein, was refluxed for two. hours, after which. time the solution was no longer alkaline to phenophthalein; A further quantity of 50% aqueous sodium hydroxide solution was added sufficient to make the mixture alkaline and refluxing was resumed and continued for one and one-half hours. Ten m1. of concentrated hydrochloric acid was then added and the mixture was refluxed for twenty minutes. The mixturewas cooled'to 20 C. and filtered, and the solid. thus collected was washed with Water until; the. wash liquor was free of acid USiHg COngO 10 red paper. The product thus obtained was 4,4- bis- (benzimidazol-Z -yl)stilbene, identical with the product described above in Example 1. p

EXAMPLE 5 4,4'-bis(benzimiduzol-Z-yl)stilbene A. To a well-stirred mixture of 91 g. of o-phenylenediarnine, 630 ml. of chlorobenzene, 100 g. of sodium carbonate, and 250 ml. of water heated to C. there was added out of a heated dropping funnel during a period of ten minutes a solution of 105 g. of 4,4'-stilbenedicarbonyl chloride in 1400 ml. of chlorobenzene. The temperature of the reaction mixture gradually rose during the addition until refluxing was initiated. The mixture was refluxed for six hours, and then cooled and filtered. The solid thus collected was washed successively with 500 ml. of hexane, 1000 ml. of a 0.25% aqueous solution of lorolbenzyldimethylarnmonium chloride, and finally water, until the product was free of quaternary ammonium chloride. The grey-white product wasthen dried in an oven. There was thus obtained 154 g. of 4,4'-stilbenedi[carbox(orthoaminoanilide) having the structural formula This compound was weakly fluorescent; it was not soluble in the ordinary solvents.

B-pIn a two-liter, three-neck flask there were placed- 800 ml. of Z-methoxyethanol and 200 g. of a wet paste of 92 g. of 4,4-stilbendi[carbox(ortho-aminoanilide)] and 108 g. of water. This mixture was stirred and heated to reflux and 46 ml. of concentrated hydrochloric acid (about 38% by weight) was dropped into the mixture during a period of thirty-five minutes and this reaction mixture was refluxed for eighteen hours. The reaction mixture was then cooled and filtered and the solid thus collected was washed with water until a sample of the wash liquor was free of acid, using Congo red paper. The washed product, which was 4,4-bis(benzirnidazol-2- yl)stilbene dihydrochloride, was suspended in 800 ml. of ethanol, 25 ml. of 50% aqueous sodium hydroxide solution was added, and the mixture was heated to reflux and filtered. The filtrate was diluted with three liters of water, and the solid which separated from solution was collected on a filter. There was thus obtained 61.3 g. of 4,4-bis(benzimidazol-Z-yl)stilbene, identical with the product described above in Example 1.

When the foregoing process of part B was repeated, but replacing the 2-methoxyethanol solvent with nbutanol, the yield of the 4,4'-bis(benzimidazol-Z-yl)- stilbene was considerably lower.

' EXAMPLE 6 4,4 -bis[5 (or 6) -methylbenzimidazcl-Zo l] stilbene and thermometer there were added 61.0 g. of N,N-dimethylaniline, 63.9 g. of 2-nitro-4-methylaniline, and 707 g. of chlorobenzene. This material was heated to 50 C. for five minutes and then a solution of 60.4 g. of 4,4'- stilbenedicarbonyl chloride in 588 g. of ortho-dichlorobenzene was' added. A solid began to separate slowly from the reaction mixture andthe reaction temperature rose to 85 C. The reaction mixture was heated at 85-90 C. for one hour and then at 95-100" C. for twenty-four hours. The reaction mixture was cooled to room temperature and filtered. The solid product thus collected was washed with 67 g. of chlorobenzene, 97 g. of methanol, and 110.25% aqueous solution of lorolbenzyldimethylammonium chloride until a clear filtrate was obtained. The product was then washed with water until the quaternary ammonium chloride had been re moved. The yellow product was dried in an oven. There was thus obtained 99 g. of 4,4'-stilbenedi[carbox- (2-nitro-4-firethylanilide)] which did not melt when heated at 320 C.

B. To a five-liter flask fitted with an agitator, thermometer, reflux condenser and dropping funnel there were added 2250 ml. of Z-methoxyethanol and 99 g. (0.177 mole) of 4,4-stilbenedi[carbox(2-nitro-4-methylanilide)]. This mixture was hea-tedto reflux temperature, then heating was discontinued, and there was added a solution of 258 g. of stannous chloride dihydrate in 510 ml. of hydrochloric acid at such a rate that refluxing was maintained by the heat of the reaction. After this addition was completed, the reaction mixture was refluxed for seven hours. Themixture was chilled in an icebox overnight and then filtered. The solid product thus collected was washed first with one liter of 1% hydrochloric acid and then with water until the solid was free of acid to Congo red. There was thus obtained 86.7 g. of 4,4'-bis[5 (or 6)-methylbenzimidazol-2-yl]stilbene dihydrochloride. This salt was suspended in 919 ml. of Z-methoxyethanol and the mixture was heated to 60 C. with stirring. There was then added 36 g. of 50% aqueous sodium hydroxide solution and the mixture .was slowly heated to reflux temperature. The mixture was filtered to remove insoluble material, consisting chiefly of inorganic salts, and the solid thus removed waswashed with 100 .ml. of boiling Z-methoxyethanol. The filtrate and wash liquor were combined and diluted in a crock with nine liters of water with vigorous stirringo: The yellow solid which separated from solution was collected on a filter and freed of alkali by washing with water. There was thus obtained 61.8 g. of 4,4- bis 5(or 6 -methylbenZimidazol-2-yl stilbene.

EXAMPLE 7 I 4,4'-bis[5 (or 6) -methoxybenzimidazol-Z-yl]stilbene A. To a mixture of 61.0 g. of N, N-dimethylaniline, 70.6 g. of 2-nitro-4-methoxyaniline, and 640 ml. of'ehlorobenzene heated to 50 C. there was added slowly with stirring over a period of eight-minutes, a hot (120130 C.) solution of 61.1 g. of 4,4-s'tilbenedicarbonyl chloride in 467 ml. of chlorobenzene. The remnants of the acid chloride solution were washed from its container OCHs into thereaction mixture with an additional 61 ml. of chlorobenzene. The mixture was heated at 85-95 C. for one hour and then at 95-100 C. for twenty-four hours. The mixture was then cooled to room temperature (about C.) and filtered, and the solid thus collected was washed successively with 61 ml. of chlorobenzene, 122 ml. of methanol, and a warm C.) 0.25% aqueous solution of lorolbenzyldimethylammonium chloride'until the wash liquor was free of chlorobenzene, The solid was finally washed with one liter of warm (50 C.) water to remove the quaternary ammonium chloride. There was thus obtained 111.2 g. of 4,4'-stilbenedi[carbox(2-nitro-4-methoxyanilide)] as a yellow solid which melted .at 311-318 C.

B. A mixture of 2,324 ml. of Z-methoxyethanol and 104 g. of 4,4-stilbenedi[carbox(2-nitro-4-methoxyanilide)] was heated to reflux, then heating was discontinued and a solution of 266 g. of stannous chloride dihydrate in 527 ml. of concentrated hydrochloric acid was added slowly with stirring over a period of seven minutes. Refluxing was then resumed and continued for fifteen hours. The reaction mixture was cooled to 15 C. and filtered, and the solid thus collected was washed with water until free of acid and dried. This product, which was 4,4-bis[5(or 6)-methoxybenzimidazol-Z-yl1stilbene dihydrochloride, was suspended in 1,076 ml. of Z-methoxyethanol and heated to C. To this mixture there was added 50.6 g. of 50% aqueous sodium hydroxide solution. -The temperature of the mixture rose to C. and almost all of the solid dissolved. The mixture was heated to reflux temperature and filtered. The residue thus removed waswashed with 106 ml. of boiling 2-methoxyethanol, and the washings were combined with the filtrate. This solution was slowly diluted with eleven liters of warm (60 C.) water. -The yellow solid which precipitated from solution was collected on a filter, washed with-water until free of alkali, and then dried in an oven. The product thus obtained,.which was 4,4'- bis[5(or 6)methoxybenzimidazol-Z-yl]stilbene, weighed 81.2 g. It was soluble in polyethyleneglycol HO CH (CI-I OCH 'CH OH of average molecular weight 200 (Carbowax 200) containing alkali. The fluorescence of this solution, though yellower than that exhibited by 4,4-bis(benzirnidazol-2- yl)stilbene, was far more intense than that of the latter lit A. A mixture of 72.5 g. of 2-nitro-4-chloroaniline,

.. 61.0 g. of N,N-dimethylaniline, and 640 ml. of chlorobenzene was heated to 50 C. and there was then added slowly over a period of five minutes, with stirring, a hot (125'130 C.) solution of 61.0 g. of 4,4'-stilbenedicarbonyl chloride in 474 ml. of chlorobenzene. The residual acid chloride solution was washed from its container into the mixture with 61 ml; of chlorobenzene. The mixture was heated at -90 C. for one hour and then at 75 'C. fortwenty-four hours. The reaction'mixture was 'cooled .to room temperature (about 25 C.) and filtered.v The solid thus collected was washed sue cessively with 61 ml. of chlorobenzene, 122 ml. of methanoLand suflicient warm (50 C.) 0.25% aqueous solution of lorolbenzyldimethylammonium chloride to yield colorless washings. The solid was finally washed with water until the quaternary ammonium chloride had been removed and the product was dried. There was thus obtained 107.2 g. of 4,4'-s tilbenedi[carbox(2-nitro-4- :chloroanilide) B. A mixture of 100 g. of 4,4'-stilbenedi'[carbox(2- nitro-4-chloroanilide)] and 2,200 ml. of 2-methoxyethanol was heated to reflux temperature, then the source of heat was removed, and there was added with stirring a solution of 252.3 g. of stannous chloride dihydrate in 499 m1. of concentrated hydrochloric acid at such a rate as to maintain rapid refluxing. The reaction mixture was refluxed for twenty hours and was then cooled to 25 C. and filtered. The solid thus collected was washed with water until free of acid and dried. The yellow product thus obtained, which was 4,4'-bis[5 (or 6)- chlorobenzimidazol 2 yllstilbene dihydrochloride, was mixedwith 1,250 ml. of 95 ethanol and 64 g. of 50% aqueous sodium hydroxide solution. This mixture was refluxed until substantially all of the yellow solid had dissolved and then filtered hot to remove insoluble inorganic salts. The solid residue on the filter was washed with 100 ml. of 95% ethanol and all of the filtrates were combined and were then diluted slowly with seven liters of warm (50 C.) water. The pale yellow solid which separated from solution was collected on a filter, washed free of alkali with water and dried. There was thus obtained 83.2 g. of 4=,4-bis[5(or 6).-chlorobenzimidazol-2- yl stilbene. EXAMPLE 9 4,4'-bis(1-methylbenzimidazol-Z-yl)stilbene CH3. A; To a hot (85 C.) and stirred mixture of 4.8 g. of

N-m ethyl-ortho phenylenediamine, 294. ml. of 'chloro benzene, 46,6 got sodium carbonate and 1-17 mlfof water there was added slowly from a heated dropping funnel a solution of 51.7 g. of 4,4'-stilbenedicarbonyl chloride in 717 ml. of chlorobenzene. This addition, which required about. twenty minutes, was followed by a six-hour period of refluxing of the reaction mixture. A small quanity of aqueous'sod-i um carbonate solution was added to the mixture. during the course of the reflux period to keep it alkaline to phenol-phthalein. The reaction mixturev was cooled to 5 C. and filtered, and the solid thus collected waswashed with hexane and then with water. The solid, was then slurried in hexane and filtered. The product; thus obtained, which was 4,4- stilbenedi{carbox ortho-methylamino )anilide] weighed 41.0 g. 4

B. A mixture of 410g. of 4,4-stilbenedi{carbox[ortho- (methylamino)anilidel} and 1158 ml. of 2-methoxyethanol was heated to reflux temperature and 115.8 ml. of concentrated hydrochloric acid was: added dropwise with stirring to the refluxing mixture. All of the solid dissolved during this addition. The solution was refluxed for a further period of. one hour. The solution was then distilled. to remove about two-thirds of the 2-methoxyethanol and; the residue. was chilled overnight in a ref-rigerat or. The solid which hadseparated from solution was then collected 'on a filter. There was thus obtained 24.4 g. of 4,4-bis(1-methylbenzimidaz0l-2-yl)stilbene dihydrochloride. A mixture of this product and 965 ml. of Z-rnethoxyethanol was heated to reflux. temperature and 450ml. of concentrated hydrochloric acid was slowly added with stirring to dissolve the solid. The solution thus obtained was poured into an agitated mixture of 550 g. of 50% aqueous sodium hydroxide solution and 500 ml. of ethanol. The mixture became hot and a cream colored solid separated from solution. The mixture was distilled until 574 ml. of distillate had been collected. The residue was cooled to 50 C. and 1250 ml. of water was added very slowly with good agitation. The mixture was cooled to room temperature while continuing the agitation and was then filtered. The collected solid was washed with water until free of alkali and dried. There was thus obtained 4,4-bis-(1-methylbenzimidazol-2-yl) stilbene.

EXAMPLE 10 M ethylation of 4,4 -b i.s benzim idazol-Z -yl sti lbene A. To a solution of 10.3 g. (0.025 mole) of 4,4-bis- (benzimidazol-Z-yl)stilbene in ml. of Z-methoxyethanol there was added 4 ml. of a 50% aqueous solution of sodium hydroxide. The mixture was heated to 65 C. and 3.14 g. (0.025 mole) of methyl sulfate was added. The reaction mixture was heated at 70 C. for three hours and then 1.5 ml. of water was added. The reaction mixture was cooled to 20 C. and filtered. The solid thus collected was washed with water and then dried at 70 C. There was thus obtained 9.9 g. of 4-(benzimidazol-2-yl)- 4-(1-methylbenzimidazol-2-yl)stilbene, having the structural formula B. Amixture of 8.7 g. (0.021 mole) of 4,4'-bis(benzimidazOl-Z-yDstilbene, 65 ml. of 2-methoxyethanol, and 4.46 ml. of a 50% aqueous solution of sodium hydroxide was heated to 65 S. and 3.19 g. (0.025 mole) of methyl sulfate was added. The reaction. mixture was heated at 70 C. for one hour and: then 3.19 (0.025 mole) of methyl sulfate was added; after which the mixture was refluxed for one and one-half hours. There was then added ml. ofwater to the mixture and, it was cooled to room temperature (about 25 C.). The mixture was filtered and the solid, thus collected was washed with water and then dried at 75 C. Therewas thus obtained 8.1 g. of 4,4;-bis(1-methylbenzimidazol 2-yl)stilbene, identical with 'theproduct described above in Example 9.

EXAMPLE l1 carboxymethylarion 0 4,4 b1s(benzimidazal-Z-yl) stilbene 15 I refluxed for two hours, cooled to about 50 C. and another 0.95 g.- monochloroacetic acid .wasadded. Thereaction mixture was refluxed fora further period of two hours and thencooled to room temperature (about 25 C.). Fiftyml. of water was'added dropwise to the reaction mixture, and the solid which had separated from solution was collected on a filter, washed with about 60 ml. of water, and dried in an oven. There was thus obtained 3.2 g. of 4-(benzimidazol-2-yl)-4'-[1-(carboxymethyl)- benzimidazol-2-yl]-stilbene, having the structural formula CHPCOOH This compound reacts with bases, for example alkali and alkaline earth hydroxides, to form the corresponding carboxylate salts.

EXAMPLE 12 Carboxymethylation f 4-(benzimidaz0l-2-yl) -4'- (1 -methylbenzimidazol-Z-yl) stilberie A mixture of 4.26 g. (0.01 mole) of 4-(benzimidazol- 2-yl)-4-(1-methylbenzimidazol-2-yl)stilbene, 1 ml. of 50% aqueous sodium hydroxide solution, and 25 ml. of 2-methoxyethanol was heated to 80 'C. to dissolve the solid and 0.95 g. (0.012 mole)"of 'chloroacetic acid was added. A yellow precipitate appeared immediately in the reaction mixture. The mixture was refluxed for two hours, then cooled to 90 C., and another 0.95 g. of chloroacetic acid was added. The mixture was refluxed for two hours, then cooled to 90 C. and 50 ml. of water was added. The mixture was then diluted with 200 ml. of hot Water, cooled to room temperature, and filtered. The solid thus collected was washed with water and dried. There was thus obtained 4.6 g. of 4-[1- (carboxymethyl)benzimidazol 2 yl] 4' (1.- methylbenzimidazol-Z-yl)stilbene having the structural formula EXAMPLE 13 Cyanaethylation of 4,4-bis(benzimidazol-Z-yl)stilbene A. A mixture of 4.1 g. (0.01 mole) of 4,4-bis(benzimidazol-2-yl)stilbene, 1.6 g. of a 50% aqueous solution of sodium hydroxide, and 25 ml. of Z-methoxyethanol was heated to dissolve the solid. To the warm (50 C.) solution was added 0.53 g. (0.01 mole) of acrylonitrile and this reaction mixture was heated at 50 C. for two hours.

"16' There was thus produced 4-(benzimidazol-2-yl)-4-[1- (2 cyanoethyl)benzimidazol 2 yl]stilbene, having the structural formula 5 I OHa-GHr-CN The reaction mixture containing this product was mixed with 5 ml. of water and the mixture was refluxed for two hours to hydrolyze the cyano group. The reaction mixture was cooled to 50 C., diluted with 200 ml. of water and filtered. The solid thus collected was washed with water and dried. There was thus obtained 3.9 g. of 4 (benzimidazol 2 yl) 4' [1 (2 carboxyethyl)- benzimidazol-2-y11stilbene, having the structural formula V I N 3 4 CH- C g JHr-CHr-OOOH l OHI-O PON N r-OHrCN To the reaction mixture containing this product were added '1.6 g. of a 50% aqueous solution of sodium hydroxide and 5 ml. of water and the mixture was refluxed for two hours to hydrolyze the cyano groups. The reaction mixture was cooled to 50 C., diluted with 200 ml. of water and filtered. The solid thus collected was washed with water and dried. There was thus obtained 7 4.1 g. of 4,4-bis[1-(2-carboxyethyl)benzimidazol-2-yl]- stilbene, having the structural formula N C CH C Hr-OHr-COOH C CH O IBPCHa-COOH This compound was soluble in alkaline ethanol. It

had an especially high substantivity to cellulose acetate.

EXAMPLE l4 Cyanoethylation of 4-(benzimidazol-2-yl)-4-(1-methylbenzimz'dazol-Z-yl)stilbene 4'-(1-methylbenzimidazol-2-yl)stilbene, having the structural formula 1 The reaction mixture containing this product was mixed .with 5 ml. of water and the mixture was refluxed for two hours to hydrolyze the cyauo group. The mixture was mixed with 250 ml. of water and filtered. The solid thus collected was washed with water and dried in an oven at 70 C. There was thus obtained 4.3 g. of 4-[1-(2- carboxyethyl)benzimidazol 2 yl] 4' (1 methylbenzimidazol-2-yl)-stilbene having the structural formula EXAMPLE 15 Chlorobenzylation of 4,4-bis(benzimidazol- 2-yl)stilbene A mixture of 8.2 g. of 4,4-bis(ben zimidazol-2-yl)stilbene, 3.0 g. of potassium hydroxide, and 40 ml. of 2-(2- vfethoxyethoxy)ethanol was heated to C. to dissolve the-solid. The solution thus obtained was heated and stirred on a steam bath and g. of ortho-chlorobenzyl chloride was dripped into the solution slowly during a period ofthirty minutes. The reaction mixture was then heated at C. for fifteen minutes. The hot solution was filtered to remove a precipitate of potassium chloride and the filtrate was cooled to 25 C. The crystalline solid which precipitated was collected on a;filter and dried at 70 C. This product, which weighed 6.5 g. and melted at 270-280 C., was a mixture which consisted chiefly of the N,N-dialkylated derivative and a lesser amount of the monoalkylated compound, namely 4-(benzimidazol- 2 yl) 4' [1 (ortho chlorobenzyl)benzimidazol 2- yl] stilbene having the structural formula C? (MO The separation of these two products can be carried out by conventional fractionation, as by recrystallization. For example, for recovery of the N,N-dialkylated product, the mixture obtained above was recrystallized first from 200 ml. of N,N-dimethylformamide and then from 40 ml. of boiling ortho-dichlorobenzene, followed by washing with benzene and ether, and drying under reduced pressure at 100 C. The nearly colorless crystalline needles thus obtained consisted of 4,4'-bis[1-(orthochlorobenzyl)benzimidazol 2 yl]stilbene, having the structural formula The product weighed 2.5 g. and melted at 280 C. It was insoluble in alcoholic sodium hydroxide solution.

Analysis.Calculated for C H N Cl C, 76.14%; H, 4.68%; N, 8.47%; CI, 10.72%. Found: C, 75.91%; H, 4.48%; N, 8.41%; Cl, 10.90%.

EXAMPLE 16 Allylation of 4,4-bis(benzimidazol-Z-yl)stilbene A. To a mixture of 60 g. (0.147 mole) of 4,4'-bis(benzimidazol-2-yl)stilbene, 280 ml. of Z-methoxyethanol, and 39 g. of a 50% aqueous solution of sodium hydroxide heated at 50 C. there was added dropwise, over a period of one hour, 12 g. (0.0157 mole) of allyl chloride. The

' reaction mixture was refluxed for sixteen hours and then was diluted with 280 m1. of water. The solid which had separated from solution was collected on a filter and washed free of alkali with Water. This solid, which weighed 60 g., consisted of the crude monoallylation product; it was purified as follows. The solid was dissolved in 400 m1. of N,N-dimethylformamide and the resulting B. By interaction of the monoallylation product descriped above with a second molecular equivalent of allyl chloride, there is obtained 4,4-bis(l-allylbenzimidazol-2-yl)stilbene, having the structural formula GHQ-C 11 Hg 7 EXAMPLE 17 Hydroxyethylation of 4;4'-bis(benzimidazol-Z-yl) stilbene To a 50 ml. ground glass wide-mouth flask equipped with acondenser the barrel of which served as a bearing for an agitator paddle there'were added 4.1 g. (0.01 mole) of 4,4-bis(benzimidazol-Z-yl)stilbene, 16.5 g. of Z-methoxyethanol and 1.8 g. of a 50% aqueous solution of sodium hydroxide. .After all of the solid had gone into solution there was added 1.7 g. (0.0212 mole) of ethylene chlorohydrin. The reaction mixture was slurried and refiuxed for one hour after which period the reaction mixture was transferred to a beaker and heated on a water bath until approximately half of the solvent had evaporated. There was then added 30 ml. of water and the mixture was allowed to cool to room temperature. The yellow solid which had separated from solution was collected on a filter and washed with water until a sample of the wash liquor was colorless and free of alkali. The product thus obtained, which weighed 4.1 g., was a yellow solid which did not melt at 350 C. It consisted chiefly of 4-(benzimidazol-2-yl)-4-[1-(2-hydroxyethyl)- benzimidazol-Z-yl]stilbene, having the structural formula Y 7 O N I CHzCHzOH which was soluble in aqueous alkaline ethanol solution,

with small amounts of unreacted 4,4-bis(benzimidazol- 2-.y1) stilbenc and 4,4'-bis l- Z-hydroxyethyl) benzimida- Z0l-2-yl1stilbene, having the structural formula N 3 CH- C N IH2C 2OH OHzOHzOH The dialkylated product was insoluble in aqueous alkaline ethanol solution and very slightly soluble in glacial acetic acid.

EXAMPLE .18

Arhixture of 8.3 g. of 4,4-bis[5 (or 6)-methylbenzimidazol-2-yllstilbene, 32.0 g. of Z-methoxyethanol, and 5.2 g. of .a 50% aqueous solution of sodium hydroxide was heated to dissolve the solid. To the warm (50 C.) and well-stirred solution there was added 2.08 g. of 2,3-dihydroxypropyl chloride and the mixture was refluxed for one and one-half hours. There was thus produced 4- [5'( or 6) -methylbenz.imidazol-2-yl] -4- l-(2,3-dihydroxypropyl) -5 (or 6 -methylbenzimidazol-Z-yl] stilbene, having the structural formula To the reaction mixture containing the above compound, there was added a second portion of 2.08 g. of 2,3-dihydroxypropyl chloride and the mixture was refluxed for one and one-half "hours. The mixture was then cooled and diluted with 575 ml. of warm (50 C.) water and filtered. The solid thus collected was washed with water until free of alkali and then dried in an oven. There was thus obtained 8.9 g. of solid consisting chiefly of the rn'onoalkylated compound above and 4-[5 (or 6)-methylbenzimidazol-Z-yl] 4'-{l-[2 -hydroxy 3-(2,3-dihydroxypropoxy)propyl]-5 (or 6)-methylbenzimidazol 2 yl}stilbene having the structural formula and a small amount of unreacted 4,4-bis[5(or 6)-methylbenzirhida-zol-Z-yl]stilbene starting material.

21 EXAMPLE 19 O-CH To the reaction mixture containing the above compound there Was added a second 2.08 g. portion of 2,3-dihydroxypropyl chloride. The mixture was refluxed for one and one-half hours and then was cooled and diluted with 290 ml. of warm (50 C.) water. The diluted mixture was filtered and the solid thus collected was washed with water until free of alkali, and dried. There was thus obtained 12 g. of yellow solid which consisted chiefly of the abovementioned monoalkylated product and an O-alkylation derivative thereof, namely 4-[5(or 6)-methoxybenzimid- 4 azol 2-yl]-4'-{1-[2-hydroxy-3-(2,3-dihydroxyprop oxy)- propyll -5 (or 6)-methoxybenzimidazol-2-yl}stilbene having the structural formula O--CH| 6H2 t'JHOH cm-o-om-onon-cmorr along with some unalkylated starting material.

EXAMPLE 2o 5 Dihydroxypropylation 0f 4,4'-bis[5(0r 6) -chl0r0benzimidaz0l-2-yl1stilbene A mixture of 50 g. of 4,4-bis[5 (or 6)-chlorobenzimidazol-Z-yl] stilbene, 50 g. of a 50% aqueous solution of sodium hydroxide, and 209 ml. of 2-methoxyethanol was refluxed for ten minutes to dissolve the solid. After adjusting the temperature of the resulting solution to 50 C. there was added 11.5 g. of 2,3-dihydroxypropyl chloride 8 together with some unalkylated starting material.

and the mixture was refluxed for one and one-half hours. There was thus produced 4-[5(or 6)-ch1orobenzimidazol- 2-yl]-4'-[1-(2,3 dihydroxypropyl 5 (or 6) chlorobenzimidazol-2-yl1stilbene, having the structural formula CH-- I C C1 O 0 A The reaction mixture containing the above compound was cooled to 50 C., a second portion of 11.5 g. of 2,3-dihydroxypropyl chloride was added, and the mixture was refluxed for one and one-half hours. The mixture was then cooled to 60 C. and 1800 ml. of warm (50 C.) water was added in a thin stream with good agitation. The diluted mixture was filtered to collect the yellow solid which precipitated. The collected solid was washed free of alkali with water and dried. There was thus obtained 54.6 g. of yellow product consisting chiefly of the monoalkylated product mentioned above'and 4- [5 (or 6)-chlorobenzimidazol-Z-yl]-4-{1[2-hydroxy 1 3 (2,3-dihydroxy propoxy)propy1]-5 (or 6)-chlorobenzimidazol 2 yl}stilbene having the structural formula I HOH CHr-O-CHz-CHOH-CHzOH This product was less soluble in alkaline ethanol solution than were the corresponding unchlorinated compound (Examp'l 28B) and the dimethoxy analog (Example 19).

EXAMPLE 21 Hydroxyethoxy-hydroxypr0pylati0n of 4,4-bis(benzimidazol-Z-yl] stilbene To a one-liter, three-neck flask fitted with a stirrer, thermometer, and reflux condenser there were added 82 g. of 4,4'-bis(benzimidazol-2-yl)stilbene (0.2 mole), 394

g. of Z-methoxyethanol, and 32 g. of a 50% aqueous solution of sodium hydroxide. This mixture was heated-to dissolve all of the solid and the temperature of the solution thus obtained was adjusted to 50 C. There was then added in one portion 30.8 g. (0.2 mole) of 2-hydroxy-3- (2-hydroxyethoxy)propyl chloride. The reaction mixture was refluxed for two hours. There was thus produced 4- (benzimidazol 2-yl) -4'-{1-[2-hydroxy 3 (Z-hydroxyeth- 23 oxy)propyl]benzimidazol-2-yl}stilbene, having the structural formula N CHr-CHOH-CHa-OCHaOHnOH To the warm (42 C.) reaction mixture containing the above compound there was added a further portion of 6.16 g. (0.04 mole) of 2-hydroxy-2-(2-hydroxyethoxy)- propyl chloride and the mixture was refluxed for one and one-half hours. There was then distilled from the reaction mixture 300 ml. of solvent, the residue in the still was cooled to 60 C., and 600 m1. of warm (60 C.) water was added (in subsequent preparations the mixture was seeded at this point with a small amount of the expected monoal-kylation product noted above). The mixture, which contained solid which had separated from solution, was stirred vigorously, and then cooled to room temperature (about C.) and filtered. The solid thus collected was washed with water until a sample of the filtrate was free of alkali. There was thus obtained 96 -g. of pale yellow product which consisted chiefly of 4- (benzimidazol-2-yl)-4'-{1-[2-hydroxy 3 (2-hydroxyethoxy)propyl]benzimidazo12-yl}stilbene together with small amounts of the O-alkylated derivative thereof having the structural formula HOH 24 3-(2,3-dihydroxypropoxy)propyl chloride was added, and the mixture was refluxed for a further period of two hours. The reaction mixture was then cooled to C. and 200 ml. of cold water was added slowly. The solid which had separated from solution was collected on a filter, washed free of alkali with water and dried in an oven. There was thus obtained 9.2 g. of yellow solid which consisted 3-dihydroxypropoxy)propyllbenzimidazol 2 yl}stilbene (identical with the compound obtained in Example 28B by a different method).

EXAMPLE 23 Hydroxyethoxyethoxy-hydr0xypropylati0n of 4,4 -bis( benzimidazol-Z-yl )stilbene To a 100 ml. flask fitted with a stirrer and reflux condenser there was added 8.2 g. of 4,4'-bis(benzimidazol- 2-yl)stilbene, 33 ml. of 2-methoxyethanol, and 4.0 g. of a 50% aqueous sodium hydroxide solution and the mixture was heated to dissolve the solid. The temperature of the solution thus obtained was adjusted to 50 C. and there was added 7.25 g. of 2-hydroxy-3-[2-(2-hydroxyethoxy)ethoxy] propyl chloride. The reaction mixture was refluxed for two hours and then cooled to 50 C. There was added a further portion of 1.4 g. of 2-hydroxy-3- [2-(2-hydroxyethoxy)e'thoxylpropyl chloride and the mixture was refluxed for one and one-half hours. To the reaction mixture Was added 300 ml. of cold water with stirring. The solid which had separated from solution was collected on a filter, washed free of alkali with water and dried in an oven. There was thus obtained 9.8 g. of product consisting chiefly of 4-(benzimidazo-2-yl)-4- {1 {2 hydroxy-3-[2-(2-hydroxyethoxy)ethoxy]propyl} and unreacted 4,4'-ois(benzimidazol-Z-yl)stilbene starting material. The product was slightly soluble in ethanol, acetone, and 2-methoxyethanol and insoluble in non-polar solvents. It was soluble in alkaline ethanol solutions.

EXAMPLE 22 Dihydroxypropoxy-hydroxypropylation of 4,4-bis(benzimidazol-Z-yl) stilbene benzimidazol-2-yl}stilbene, having the structural formula /N GE NIJ This compound was also obtained by another method as described in the next example.

2 EXAMPLE 24 Hydroxyethylation of (bmzimidazoZ-Z-yl)-4-1-[2-hydroxy 3-(2-hydroxyeth0::y)propyl]benzimidazol-Z-yl stilbene To a 200 ml. three-neck flask fitted with a magnetic stirrer, gas one-inlet tube and U-tube manometer filled with one inch of mercury there were added 10.6 g. of.

the first thirty minutes of this period. The reaction mixture was then cooled to 40 C. and diluted slowly with 300 ml. of water at 40 C; The diluted mixture was cooled to C. and the solid which had separated from solution was collected on a filter and washed free of alkali with water. There was thus obtained 11.6 g. of yellow solid which consisted chiefly of 4-(benzimidazol 2 y1)- 4' [1 {2 hydroxy 3 [2 (2 hydroxy ethoxy)ethoxyl-propyl}benzimiclazol-2-yl]stilbene.

EXAMPLE r Sulfo-hydroxypropylation of 4,4-bis(benzimiaazol-Z-yl)- stilbene To a 100 ml. flask fitted with a stirrer and reflux condenser there were added 4.84 g. of 4,4-bis(benzimidazol- 2-yl) stilbene dihydrochloride, 25 ml. of Z-methoxyethanol,

There was thus produced 4-[5( or 6)-chlorobenzimidazol- 2 'yl]-4'-[ l-{2-hydroxy-3- [2- (2-hydroxyethoxy) ethoxy] propyI}-5(or 6)-chlorobenzimidazol-Z-yl]stilbene, having the structural formula on -o O1 Q )0 a /N V Q01 O\ I) The reaction mixture containing the above compound was cooledto roomtemperature (about 25 C.), a second 6.0 g. portion of 2-hydroxy-3-l2--(2-hydroxyethoxy)ethoxylpropyl chloride was added, and the mixture was re fluxed for one and one-half hours. The reaction mixture was cooled to room temperature and 360 ml. of cold water was added. The diluted mixture was filtered and the solid thus collected was washed free of alkali with water. The solid was dried in an oven and then was ground. There was thus obtained 11.3 g. of yellow powder which consisted chiefly of 4-[5'(or 6)-chlorobenzimidand 3.6 g. of a 50% aqueous sodium hydroxide solution.

collected was washed with water and dried in an oven.

There was thus obtained 5g. of solid which consisted chiefly of the sodium salt of the 4-(benzimidazol 2-yl)- 4"- [1 (2 hydroxy-Z-sulfopropyl)benzirnidazol-Z-ylJ- stilbenehaving the formula no i l...

HOH

HaSOaH EXAMPLE 26 Hydroxyethoxyethoxy-hydroxypropylation of 4,4- [5(0r 6 )-chlorobenzimidazol-Z-yllstilbene A mixture of 10.0 g. of 4,4'-[5 (or 6)-chlorobenzimidazo1-2'-y1]stilbene, 41.8 ml. of Z-methoxyethanol, and 5.7 g.

, of a 50% "aqueous solution of sodium hydroxide was refluxeduntil the solid had dissolved. The resulting solution was cooled to 50 C., 6.0 g. of 2-hydroxy-3-[2-(2- hydroxyethoxy)ethoxylpropyl chloride was added, and

the mixture was refluxed for one and one-half hours.

"and the mixture was refluxed for two hours.

oxanonadecyl-5(or 6)-chiorobenzimidazol 2-yl]stilbene, an O-alkylated derivative of the N-monoalkylated compound above.

EXAMPLE 27 Hydroxyethoxy-hydroxypropylation of a mixture of 4,4- bis-(benzimidazol-Z-yl)stilbene and 4-(benzimz'dazob2- yl) -4-(1-mthylbeniimidazol-Z-yl) stilbene ,8.0 g. of crude 4-(brenzimidazol-2-yl)-4'-(l-methylbenzimidazol-Z-yl)stilbene which contained some 4,4-bis- (benzimid-azoLZ-yl)stilbene was mixed with ml. of 2- methoxyethanol and 2.98 g. of a 50% aqueous solution of sodium hydroxide and the mixture was heated to dissolve thesolid. To the hot (70 C.) solution there was added 2.87 g. of 2-hydroxy-3-(Z-hydroxyethoxy)-propyl chloride The reaction mixture was cooled to about 60 C. and a further 2.87 g. portion of 2-hydroxy-3-(2-hydroxyethoxy)propyl chloride was added. The mixture was refluxed for two hours, then cooled to 50 C., and 200 ml. of water was added. A gum separated from solution and this solidified on stirring. To the mixture there was added 300 ml. of water and the solid was collected on a filter, washed with water, and dried at 70 C. There was thus obtained 10.5 g. of product which consisted chiefly of a mixture of 4 (1 methylbenzimidazol-Z-yl)-4'-{1-[2-hydroxy-3- (2 hydroxyethoxy)propyl]benzimidazol 2 yl}stilbene, having the structural formula /N V err-O-o\ (EH3 I N -Q I] N 6H3 JHOH CHz-O-CHzCHzOH 27 and the O-alkylated derivative thereof having the structural formula HOH 23 arated from solution. The filter cake was washed with water until a sample of the wash liquor was free of alkali together with a small amount of 4 (benzimidazol 2 as determined by testing with phenolphthalein paper and yl) 4 {1 [2 hydroxy 3 (2 hydroxyethoxy) propyllbenzimidazol 2 yl}stibene derived from the 4,4- bis(benzimidazol-2-yl)stilbene in the starting material. The mixture of compounds obtained in this reaction was soluble in glacial acetic acid.

EXAMPLE 28 Dihydroxypropylation of 4,4-bis(benzimidazol-Z-yl)- stilbene The procedures and products described in this example represent preferred embodiments of my invention. When these products were incorporated into detergent-s, the detergent compositions so obtained gave a brilliant bluewhite fluorescence to White fabrics treated therewith and repeated application to the fabrics did not cause development of an undesirable coloration, but instead the whiteness of the fabrics increased.

A. In a three-liter, three-neck flask fitted with an agitator, thermometer, and condenser there were placed 317 g. (0.78 mole) of 4,4'-bis(benzimidazol-Z-yl)stilbene, 1330 g. of 2-methoxy-ethanol, and 214 g. of a 50% aqueous solution of sodium hydroxide. After all of the solid had gone into solution, the temperature of the mixtur was adjusted to 50 C. and there was then added in one portion 86.5 g. (0.78 mole) of 2,3dihydroxypropyl chloride. The reaction mixture was refluxed for one .and one-half hours. There was thus produced 4-(benzimidazol 2 yl') 4' l (2,3 dihydroxypropyl) benzimidazol-2-yllstilbene, a yellow compound having the struc-.

tural formula OHn-CHOH-CHZOH (2,3 "dihydroxypropoxylpropylbenzimidazol 2 yl}- stilbene, having the structural formula The yellow pro-duct also contained some of the monoalkylated compound as well as a small amount of 4,4'-bis- (=benzimidaz-ol-2-yl)-stilbene. The product was slightly soluble in 2-methoxyethanol and Z-ethoxyethanol and insoluble in methanol, ethanol, and glacial acetic acid. 'It was soluble in NJJ-dimethylformamide to the extent of about 20%. In monosodium salt form, the product was very soluble in alkaline ethanol and alkaline 2-ethoxyethanol; in the former solvent, the solubility was about 20%, and in the latter, about 33%.

C. The mixture of products described in part B above was useful without further treatment as a whitening and brightening agent. However, for incorporation into white solid detergents, I prefer to remove or eliminate from the mixture all unreacted 4,4'-bis(benzimidazol-2- yl)stilbene starting material. I have found that the unalkylated compounds of Formula I may cause yellowing of some solid white detergents containing 10-20% of water and, although this does not cause any diminution of the whitening and brightening properties of the detergent comp-osition, "the detergents thereby may become less marketable. The white color of the yellowed detel gent is however readily restored by drying to bring the water content thereof below about 10% by weight. The following method illustrates the removal of 4,4'-bis(benzimidazol-2-yl)stilbene from the mixture of products.

A suspension of 5 g. of the product of part B in 30 ml. of glacial acetic acid was stirred for one hour. The mixture was then filtered to collect insoluble material, which consisted of 4,4'-bi-s(benzimidazol-Z-yl)stilbene diacetate. The filtrate was diluted with 200 ml. of water. Centrifugation caused the separation of a very finely 29 divided solid from the mixture. The supernatant liquid was made basic by treatment "with ammonia, and'thc mixture was boiled to coagulate the fine powder and then was cooled and filtered. The precipitate thus collected was washed with water until free of ammonia and then dried. This solid, which weighed 2.7 g. was suspended in 150 ml. of 95% ethanol, the mixture was boiled for fifteen minutes, and the solution thus obtained filtered by gravity while hot. The insoluble residue thus removed was washed with a few ml. of ethanol. The wash liquor and filtrate were combined, concentrated to about 75 ml., and diluted with a small amount of water until crystals began to appear. The solution was cooled and filtered to collect 1.8 g. of solid. Recrystallization of this product twice from N,N-dimethylformamide and once from 2-ethoxyethanol yielded 4-(benzimid-azol-2-yl- 4 {1 [2 hydroxy 3 (2,3 dihydroxypropoxy)- propyl]-benzimidazol-2-yl}stilbene, which melted at 225 C D. Further alkylation of the mixture'of products obtained in part B above yielded O-alkylated derivatives of the 4 benzimidazol 2 yl 4 {1 [2 hydroxy 3- (-2,3 dihydroxypropoxy)propyl]benzimidazol 2 yl}- stilbene component and resulted in the elimination of the 4,4'-bis(benzimidazol-2-y1)stilbene component by conv-erting it to N-monoalkylated and N,N'-dialkylated derivatives. As in the case of the product purified by the method of part C above, these 4,4'-bis(benzimidazol-2- yl)stilbene-free mixtures were found to be especially useful as whitening and brightening agents for incorporation into white solid detergents. It was found that the progressive elimination of the N,N'-unalkylated compound could be followed conveniently by use of a color test on samples of the reaction mixture; this is illustrated below, using ethylene oxide as the alkylating agent.

120 g. of the mixture of products obtained above in part B, which contained a small, undetermined amount of 4,4'-bis(benzimidazol-Z-yl)stilbene, was mixed-with 360 ml. of Z-methoxyethan-ol and 27 g. of a 50% aqueous solution of sodium hydroxide in a one-liter three-neck flask fitted with a thermometer, gas inlet to the void above the reaction mixture, a U-shaped manometer filled with one and one-half inches of mercury, and a high-speed agitator. The mixture was heated to 74 C. to dissolve the solid. The presence of 4,4' bis(benzimidazol-Z-yl)- stilbene in the mixture was detected qualitativelyby the following test: V

A 0.1 ml. sample of the mixture was mixed with 35 ml. of 95 ethanol and to a 1.0 ml. aliquot of the resulting yellow solution there was added dropwise, from a 1 m1. graduated pipette, 0.01 N nitric acid until the yellow color disappeared (in this instance, 0.15 ml. of the acid was required). The colorless solution was diluted with water to a volume of 2.0 ml. of a solution of 1.0 g. of chromic nitrate [canon 011,0]

in 206 m1. of water. The development of a yellow color in the solution indicated the presence of-4,4-bis(benzimidazol-2,yl)stilbene.

' Ethylene oxide was passed into the reaction vessel while maintaining the reaction mixture at 7480 C. At intervals of ten-fifteen minutes, 0.1 ml. samples of the reaction mixture were removed and tested as indicated above for presence of 4,4'-bis (benzimidazol-Z-yl)stilbene. After seventy minutes of passage of ethylene oxide into the reaction vessel, the chromic nitrate solution failed to cause development of a yellow color in above test showing that no 4,4'-bis(benzimidazol-Z-yl) stilbene remained in the reaction mixture. The total weight of ethylene oxide absorbed by the reaction mixture was 22.1 g.

The reaction mixture was transferred to a two-liter beaker, cooled at 50 C., and 1500 ml. of warm (50 C.) water was added slowly with stirring. Then 400 g. of ice was added to cool the mixture to room temperature and There was then added eight drops;

deadbeathe yellow solid which had separated from solution was collected on a filter and washed free of alkali with water.

There was thus obtained 118 g. of yellow product which consisted chiefly of a mixture of O-hydroxyethylated and, to a lesser extent, N-hydroxyethylated, derivatives of 4-(benzimidazol-2-yl)-4'-{1-[2-hydroxy-3-(2,3-dihydroxypropoxy]-propylbenzimidazol-2-yl}stilbene together with small amounts of 4-(benzimidazol-2-yl) 4-[1-(2-hydroxyethyl)benzimidazol-2yl]-stilbene and 4-(benzimidazol-2- yl) 4'-{l [2 (2 hydroxyethoxy)ethyl]benzimidazol- 2-yl}stilbene. The components of this mixture, although separable by conventional fractionation procedures, are all whitening and brightening agents and, moreover, the mixture was found to have excellent stability in the presence of dried white detergents and to whiten these detergents. Therefore, for practical purposes, it was found to be preferable to use the mixture of the several compounds obtained as described above without purification.

E. When the product of part D above is reacted further with ethylene oxide, or alternatively when the process of hydroxyethylation of the product of part B is continued for some time after the 4,4'-bis(benzimidazol-Z-yl)stilbene has disappeared from the mixture as determined by the color test described above, there are obtained hydroxyethylated compounds having progressively increasing solubility 'in-glacial acetic acid; on the other hand, the solubility of these products in alkaline alcohol solutions decreases due to increasing proportion of N,N'-dialkylated derivatives in the mixture. These acetic acid-soluble mixtures are especially useful embodiments of the new benzimidazolylstilbenes of my invention for incorporation into detergents. The preparation of a representative mixture of this type is described below.

To a 200 ml. three-neck flask fitted with a magnetic stirrer, gas inlet, a U-shaped manometer filled with one inch of mercury, and a thermometer there were added 15 g. of 4 (benzimidazol 2 yl)-4'-[1-(2,3-dihydroxypropyl) benzimidazol-Z-yl)stilbene containing a small amount of 4,4-bis(benzimidazol-Z-yl)stilbene (prepared in the manner described in part B above), 3.0 g. of a 50% aqueous solution of sodium hydroxide, and 75 ml. of 2- methoxyethanol. The mixture was stirred and heated to dissolve all of the solid, and the solution thus obtained was then maintained at a temperature of 65-70 C. while ethylene oxide was passed into the reaction vessel above the surface of the mixture. After 9.5 g. of ethylene oxide had been absorbed (requiring about one hour) the reaction mixture was cooled to 50 C., diluted with 250 ml. of warm 50 C.) water, cooled to room temperature, and filtered. The solid thus collected was washed free of alkali with water, and dried. There was obtained in this manner 14.5 g. of yellow powder consisting chiefly of hydroxyethylated derivatives of the 4-(benzirnidazol-2- yl)-4'-[1-2,3-dihydroxypropy1)benzimidazol-Z-yl)stilbene containing 1-4 oxyethyl (OCH CH residues; representative of these is the compound having the structural formula I This mixture whitened dried detergent powders and was and silk.

3 to use in white solid detergents. The mixture was only slightly soluble in alkaline 2-methoxyethano1 and alkaline ethanol solution; it was soluble in cold glacial acetic acid.

When the benzimidazolylstilbenes described in the foregoing Examples 1-28, inclusive, were dispersed in aqueous media, the products in each instance fluoresced blue-white under ultraviolet light and showed a wide range of absorption in the ultraviolet region. Each of the products of these examples was dissolved in a suitable solvent, for instance, alkaline ethanol, alkaline 2-methoxyethanol, N,N-dimethylformamide, or glacial acetic acid, depending on the solubility characteristics of the particular product, and the solution thus obtained was poured with vigorous stirring into the desired quantity of an aqueous solution of a soap or of an anionic or non-ionic detergent. The resulting fluorescent dispersions were used to dye white and colored natural and synthetic fibers. All of the benzimidazolylstilbene products of the above examples were found to be substantive even from low concentrations, e. g. 0.0001%, in these aqueous media to white and colored fabrics of cotton, cellulose acetate, nylon, viscose rayon, orlon and silk, thereby imparting a blue-white hue to the white fabrics and brightening the colored fabrics. Moreover, these products all had relatively high stability to light as determined by accelerated exposure "tests. In the dispersions in soaps and detergents the products were substantially unaifected by a concentration of sodium hypochlorite of 0.2% by weight. My new products were thus found to be especially useful as whitening and'brightening'agents to be used in conjunction with the laundering of white and colored fabrics. The methods employed for incorporating all of the above examples of the compounds of my invention into soaps and detergents are illustrated hereinbelow. Other methods which will be readily apparent to those skilled in the art can be employed if desired.

In sap.One part by weight of the pale yellow solid described above in'Example 21 (obtained in a yield of 96 g. by the hydroxyethoxyhydropropylation of 4,4'-bis (benzimidazol-Z-yl)stilbene) was dissolved in a mixture of one part by weight of a 50% aqueous solution of sodium hydroxide and eight parts by volume of 95% ethanol. One part by volume of this solution was poured with stirring into a warm (55 C.) soap bath consisting of four parts by weight of the sodium salts of the C -C fatty acids derived from tallow and 1000 parts by weight of Water. Eight parts by volume of the resulting aqueous dispersion was diluted further by mixing with 192 parts i by volume of water containing 0.76 part by weight of the. soap indicated above. The mixture thus obtained was employed in conventional manner as a dye bath for treat; ing white fabrics of cotton, nylon, cellulose acetate, silk, and viscose rayon. Each of these white fabrics was beneficially whitened by this procedure.

In detergent Z(pm'ts are by weight).-The detergent consistedof 21.8% of a mixture of sodium lauryl sulfate and sodium dodecylbenzenesulfonates, 18.2% of sodium sulfate, and 60% of sodium triphosphateQ To a thin paste of 2000 parts of the detergent and 1500 parts of water there was added at 70 C. a solution of one part of 4,4'-bis (benzimidazol-2yl)stilbene in parts of 2-methoxyethanol and 4 parts of a 33 /3 aqueous solution of sodium hydroxide. Two hundred parts of the Well-stirred paste was poured into 5000 parts of rapidly agitated water at 60 C. To 80 ml. of this dispersion there was added 200 ml. of water and the resulting mixture was employed as a dye bath in conventional fashion to dye White fabrics of nylon, cotton, cellulose acetate, viscose rayon, orlon, To each of these white fabrics this procedure imparted a blue-white fluorescence.

In detergent Eli-Using the immediately foregoing pro- 7 triphosphate and 10.3% of sodiumcarbonate. The white fabrics were in each case beneficially whitened.

In detergent lll(parts are by weight) .A mixture of 20 parts of the145 g. of yellow powder obtained in Example 28E above, parts of tert-dodecylmercaptopolyethoxyethanol (Nonic 218), and 40 parts of glacial acetic acid was warmed on a water bath to dissolve the solid. Sixteen parts of the solution thus obtained were poured into 20,000 parts of water at 55 C.; then 8 parts of the resulting dispersion was poured into 192 parts of warm (55 C.) water, and the mixture was used to whiten and brighten white and colored fabrics of the type indicated hereinabove.

The term lorol used in this specification designates the alkyl radicals of mixed fatty alcohols derived from coconut oil.

I claim;

1. A benzimidazolylstilbene having the structural formula formula N 3 CH- O structural Z i i-Z V i. Y where 'Y is a'hydroxy-lower alkyl radical containing 2-6 carbon atoms.

*3. A 'benzim'idazolylstilbene having the formula N O CH C structual ZIP- where Y is a hydroxy-oxaalkyl-radical containing 3-15 carbon atoms.

4. A 4,4-bis [5(or 6)-(lower alkoxy)benzimidazol-2- ylJ-stilbene having the structural formula /N B y where R is a lower alkoxy radical containing 1-4 carbon atoms. a v

5. A benzimidazolylstilbene havingthe structural formula a v i O ns-(J;

Where R is a lower alkoxy radical containing 1-4 carbon atoms and Y is a hydroxy-oxaalkylradical containing 3-15 carbon atoms.

6. The compound 4,4-bis(benzimidazol-2-yl)stilbene, having the structural formula y 7;The compound 4,4'- bis[5 (or 6)-methoxybenzimidaz olz-yllstilbene, havingthe structural formula with ethylene oxide.

compound with ethylene oxide. l a

. 34" 8. The process whichcompr'ise's interacting a be azolylstilbene having the structural formula where R%, R R and R are radicals of the class consist ing of hydrogen, lower alkyl containing 1-4 carbon atoms, lower alkoxy containing 1-4 carbon atoms, and halo with an alkylating agent which is a member of the class consisting of: the esters having the formula Z-An, where Z. is'arnember. of-the class consis ing Of lower 'alkyl "con taining 1-6"carbon' atoms, 'hydroxy-low'er" alkyl contain ing 2-6 carbon atoms, 2-hydroXy 3-sulfopropyl,hydroxyoxa-alkyl containing 3-15 carbon atoms, c arb 0xy-lower alkyl containing 2-6 carbon atoms, cyano-lower alkyl containing 3-6 carbon atoms, allyl, methallyl, and monocyclic aralkyl containing 77-11 carbon, atoms and An is the anion of 'a strong' acid; 1,2-lower alkylene oxides acrylonitrile.

containing 2-6 carbon atoms; acrylonitrile; and meth- 9. The process for alk ylating 4,4'-bis(benzimidazol-2- yl)stilbene which comprises heating said compound with 2,3-dihydroxypropyl "chloride.

10. The process for alkylating 4,4'-bis(benzimidazol- 2-yl)stilbene which comprises heating said compound 11. The process for alkylating 4- (benzimidazol-2-yl)- 4-{ 1- [2-hydroxy-3 (2,3-dihydroxypropoxy)propyl] ben- 'zimidazo l-2-yl}stilbene which comprises heating said "1 2: The' process for preparing a 4,4-bis(benz' 'dazol- 2'-yl)stilbene having the structural formula where R R R and R" are radicals of the class consisting of hydrogen, lower alkyl containing 1-4 carbon atoms, lower alkoxy containing carbon atoms, van d halo,';'and Y is a member, of the class consistinglo t 11y;-

drogen lower alkyl containing 1-6 carbon atoms, and

monocyclic aralkyl containing 7-11 carbon atoms which comprises heating a 4,4'-stilbenedi[carbox(ortho-amino- V anilide)1 having the structural formula under acidic Conditions.

13. The process 'for preparing 4,4-bis(benzimi'd'azol- 2-yl)stilbene which comprises heating 4,4'-stilbenedi- [carbox(ortho-aminoanilide)] under acidic conditions.

14. The process for preparing 4,4'-bi's(benzimidazol- 2-yl)stilbene which comprises reducing stilbenedi[carbox(ortho-nitroanilide l to form stilbenediEcarbox- (ortho aminoanilide)] and heating this product under acidic conditions.

, 15. The process for preparing 4,4'-bis[5 (or 6)-met.hoxybenzimidazol-Z-yl]stilbene which comprises heating 4,4f-stilbenedi [carbox (2-amino-4-rnethoxyanilide) under acidicconditions.

'16. A 4,4-'stilbenedi[carbox(ortho-aminoanilide)] hav mg the structural .formula where R R R and R are radicals of, the class consisting of hydrogen, lower alkyl containing 1-4 carbon atoms, lower alkoxy containing 1-4 carbon atoms, and halo, and Y is a member of the class consisting of hydrogen, lower alkyl containing l-6 carbon atoms, and monocyclic aralkyl containing 7-11 carbon atoms.

17. The process for preparing a 4,4'-stilbenedi[carbox- (ortho-aminoanilide)] having the structural formula HgN E.2

where R R R and R are radicals of the class consisting of hydrogen, lower alkyl containing 1-4 carbon atoms, lower alkoxy containing 1-4 carbon atoms, and

- a as halo which comprises reducing a 4,4-stilbenedi[carbox- (ortho-nitroanilide)] having the .structural formula 18. A 4,4'-stilbenedi[carbox(ortho-nitroanilide)] having the structural formula where R R 13 and R are radicals of the class consisting of hydrogen, lower alkyl containing 1-4 carbon atoms, lower alkoxy containing 1-4 carbon atoms, and halo.

19. A benzimidazolylstilbene having the structural formula where Y is a hydroXy-lower alkyl radical containing 2-6 carbon atoms and Y is a hydroXy-oxaalkyl radical con- 7 taining 3-15 carbon atoms.

References Cited in the file of this patent UNITED STATES PATENTS OTHER REFERENCES Wright: Chem. Reviews, vol. 48, pp. 456-8, 476- (1951). 

1. AN BENZIMIDAZOLYLSTIBENE HAVING THE STRUCTURAL FORMULA 